Your work site is like a painter's empty canvas before the masterpiece emerges. So sketch out the shape of your deck and get a sense of the foundation it will need. Consider decking direction, joists, beams and then the footing locations will quickly emerge.
Loosely layout the shape of the deck with a hose or string, or spray paint a line and then remove any sod. Expose the soil and generally clean the work area prior to excavation.
Ensure there are no underground services in the area where you will be digging.
STEP 3:LAYING OUT THE FOUNDATION
Step 1 - batter boards are your friend
Use batter boards to support string (masonry string) which will demarcate the beam locations.
Step 2 - Calculate
Use triangulation and the Pythagorean hypotenuse formula to help you layout accurate locations for the holes that you will dig. Use our angle calculator
Step 3 - mark footing locations
Locate the positions of the footings and mark each of them with a large "X". You will see the importance of this later.
making batter boards from scrap lumber
Batter boards are easy to make using 2x4s and should be set several feet beyond the perimeter of the deck so they can be used throughout the excavation process. For more details on marking out the foundation elements of your deck read: Deck Building - Footing, Pier and Beam Placement
Here is how to set them up around your site to help locate where each footing will be:
Drive stakes into the ground three or four feet beyond the perimeter of the deck.
Screw horizontal 2x4s to the vertical members. Your string will rest on the horizontal boards.
Once all batter boards around the deck are up, set up string to mark the edge of the deck or the beam lines and use a plumb bob to locate critical locations.
Before you dig
Building a solid foundation for you deck takes a lot of work. But it can all be for not if you don't follow a few very important steps.
If you dig too shallow and not wide enough the pier can be pushed up with frost heave. If your footing width is wider than the thickness it can crack and break apart.
Here are the various ways of building your footings so they endure.
A STRAIGHT CONCRETE PIER
This is a great dependable style of footing that uses a standard concrete form without any flared or bell shaped bottom.
Digging is hard work. You can dig by hand using a clam shell digger and a pry bar or bring in the machinery and an auger.
By marking large X's for each footing location you will easily see each footing location even as soil accumulates around the site. And if the batter boards are still standing you can quickly run your string lines again to verify each location.
Set forms into the holes in preparation for the cement.
Set up a mixer and start mixing cement. You can use pre-mixed bags and our concrete calculator to help you plan the number of bags you will need.
Or buy some sand, stone and portland cement and mix it the old fashioned way. In either case, that mixer is going to save you some time and effort on a big project.
If you are using J bolt anchors for your post bases, be sure to have your string back on the batter boards once the cement is all poured and still wet. Verify the exact locations of the post bases so they all align.
Other important articles
INSTALLING A DECK FOOTING ON A SLOPE
What's A Good Rule Of Thumb When Footings Are On A Slope? The general rule for deck footings built on a slope are based on average soil conditions